/*
 * Copyright 2001-2005 (C) MetaStuff, Ltd. All Rights Reserved.
 *
 * This software is open source.
 * See the bottom of this file for the licence.
 */

package com.googlecode.bluetools.dom4j.tree;

import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.WeakHashMap;

import com.googlecode.bluetools.dom4j.DocumentFactory;
import com.googlecode.bluetools.dom4j.Namespace;
import com.googlecode.bluetools.dom4j.QName;

/**
 * <p>
 * <code>QNameCache</code> caches instances of <code>QName</code> for reuse both across documents and within documents.
 * </p>
 * < < < < < < < QNameCache.java
 * 
 * @author <a href="mailto:james.strachan@metastuff.com">James Strachan </a>
 * @version $Revision: 1.1 $ =======
 * 
 * @author <a href="mailto:james.strachan@metastuff.com">James Strachan </a>
 * @version $Revision: 1.1 $ >>>>>>> 1.15
 */
public class QNameCache {
	/** Cache of {@link QName}instances with no namespace */
	protected Map noNamespaceCache = Collections.synchronizedMap(new WeakHashMap());

	/**
	 * Cache of {@link Map}instances indexed by namespace which contain caches of {@link QName}for each name
	 */
	protected Map namespaceCache = Collections.synchronizedMap(new WeakHashMap());

	/**
	 * The document factory associated with new QNames instances in this cache or null if no instances should be
	 * associated by default
	 */
	private DocumentFactory documentFactory;

	public QNameCache() {
	}

	public QNameCache(DocumentFactory documentFactory) {
		this.documentFactory = documentFactory;
	}

	/**
	 * Returns a list of all the QName instances currently used
	 * 
	 * @return DOCUMENT ME!
	 */
	public List getQNames() {
		List answer = new ArrayList();
		answer.addAll(noNamespaceCache.values());

		for (Iterator it = namespaceCache.values().iterator(); it.hasNext();) {
			Map map = (Map) it.next();
			answer.addAll(map.values());
		}

		return answer;
	}

	/**
	 * DOCUMENT ME!
	 * 
	 * @param name DOCUMENT ME!
	 * 
	 * @return the QName for the given name and no namepsace
	 */
	public QName get(String name) {
		QName answer = null;

		if (name != null) {
			answer = (QName) noNamespaceCache.get(name);
		}
		else {
			name = "";
		}

		if (answer == null) {
			answer = createQName(name);
			answer.setDocumentFactory(documentFactory);
			noNamespaceCache.put(name, answer);
		}

		return answer;
	}

	/**
	 * DOCUMENT ME!
	 * 
	 * @param name DOCUMENT ME!
	 * @param namespace DOCUMENT ME!
	 * 
	 * @return the QName for the given local name and namepsace
	 */
	public QName get(String name, Namespace namespace) {
		Map cache = getNamespaceCache(namespace);
		QName answer = null;

		if (name != null) {
			answer = (QName) cache.get(name);
		}
		else {
			name = "";
		}

		if (answer == null) {
			answer = createQName(name, namespace);
			answer.setDocumentFactory(documentFactory);
			cache.put(name, answer);
		}

		return answer;
	}

	/**
	 * DOCUMENT ME!
	 * 
	 * @param localName DOCUMENT ME!
	 * @param namespace DOCUMENT ME!
	 * @param qName DOCUMENT ME!
	 * 
	 * @return the QName for the given local name, qualified name and namepsace
	 */
	public QName get(String localName, Namespace namespace, String qName) {
		Map cache = getNamespaceCache(namespace);
		QName answer = null;

		if (localName != null) {
			answer = (QName) cache.get(localName);
		}
		else {
			localName = "";
		}

		if (answer == null) {
			answer = createQName(localName, namespace, qName);
			answer.setDocumentFactory(documentFactory);
			cache.put(localName, answer);
		}

		return answer;
	}

	public QName get(String qualifiedName, String uri) {
		int index = qualifiedName.indexOf(':');

		if (index < 0) {
			return get(qualifiedName, Namespace.get(uri));
		}
		else {
			String name = qualifiedName.substring(index + 1);
			String prefix = qualifiedName.substring(0, index);

			return get(name, Namespace.get(prefix, uri));
		}
	}

	/**
	 * DOCUMENT ME!
	 * 
	 * @param qname DOCUMENT ME!
	 * 
	 * @return the cached QName instance if there is one or adds the given qname to the cache if not
	 */
	public QName intern(QName qname) {
		return get(qname.getName(), qname.getNamespace(), qname.getQualifiedName());
	}

	/**
	 * DOCUMENT ME!
	 * 
	 * @param namespace DOCUMENT ME!
	 * 
	 * @return the cache for the given namespace. If one does not currently exist it is created.
	 */
	protected Map getNamespaceCache(Namespace namespace) {
		if (namespace == Namespace.NO_NAMESPACE) {
			return noNamespaceCache;
		}

		Map answer = null;

		if (namespace != null) {
			answer = (Map) namespaceCache.get(namespace);
		}

		if (answer == null) {
			answer = createMap();
			namespaceCache.put(namespace, answer);
		}

		return answer;
	}

	/**
	 * A factory method
	 * 
	 * @return a newly created {@link Map}instance.
	 */
	protected Map createMap() {
		return Collections.synchronizedMap(new HashMap());
	}

	/**
	 * Factory method to create a new QName object which can be overloaded to create derived QName instances
	 * 
	 * @param name DOCUMENT ME!
	 * 
	 * @return DOCUMENT ME!
	 */
	protected QName createQName(String name) {
		return new QName(name);
	}

	/**
	 * Factory method to create a new QName object which can be overloaded to create derived QName instances
	 * 
	 * @param name DOCUMENT ME!
	 * @param namespace DOCUMENT ME!
	 * 
	 * @return DOCUMENT ME!
	 */
	protected QName createQName(String name, Namespace namespace) {
		return new QName(name, namespace);
	}

	/**
	 * Factory method to create a new QName object which can be overloaded to create derived QName instances
	 * 
	 * @param name DOCUMENT ME!
	 * @param namespace DOCUMENT ME!
	 * @param qualifiedName DOCUMENT ME!
	 * 
	 * @return DOCUMENT ME!
	 */
	protected QName createQName(String name, Namespace namespace, String qualifiedName) {
		return new QName(name, namespace, qualifiedName);
	}
}

/*
 * Redistribution and use of this software and associated documentation ("Software"), with or without modification, are
 * permitted provided that the following conditions are met:
 * 
 * 1. Redistributions of source code must retain copyright statements and notices. Redistributions must also contain a
 * copy of this document.
 * 
 * 2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the
 * following disclaimer in the documentation and/or other materials provided with the distribution.
 * 
 * 3. The name "DOM4J" must not be used to endorse or promote products derived from this Software without prior written
 * permission of MetaStuff, Ltd. For written permission, please contact dom4j-info@metastuff.com.
 * 
 * 4. Products derived from this Software may not be called "DOM4J" nor may "DOM4J" appear in their names without prior
 * written permission of MetaStuff, Ltd. DOM4J is a registered trademark of MetaStuff, Ltd.
 * 
 * 5. Due credit should be given to the DOM4J Project - http://www.dom4j.org
 * 
 * THIS SOFTWARE IS PROVIDED BY METASTUFF, LTD. AND CONTRIBUTORS ``AS IS'' AND ANY EXPRESSED OR IMPLIED WARRANTIES,
 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL METASTUFF, LTD. OR ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 * 
 * Copyright 2001-2005 (C) MetaStuff, Ltd. All Rights Reserved.
 */
